反射 - 获取属性名称 [英] Reflection - get property name

问题描述

我想在不使用魔法字符串的情况下将属性名称传递给函数.

I'd like to pass property names to a function without using of magic strings.

类似于:

Get<ObjectType>(x=>x.Property1);

其中 Property1 是 ObjectType 类型的属性.

where Property1 is a property of type ObjectType.

方法实现是什么样的?

推荐答案

这可以使用表达式来实现:

This can be achieved using Expressions:

// requires object instance, but you can skip specifying T
static string GetPropertyName<T>(Expression<Func<T>> exp)
{
    return (((MemberExpression)(exp.Body)).Member).Name;
}

// requires explicit specification of both object type and property type
static string GetPropertyName<TObject, TResult>(Expression<Func<TObject, TResult>> exp)
{
    // extract property name
    return (((MemberExpression)(exp.Body)).Member).Name;
}

// requires explicit specification of object type
static string GetPropertyName<TObject>(Expression<Func<TObject, object>> exp)
{
    var body = exp.Body;
    var convertExpression = body as UnaryExpression;
    if(convertExpression != null)
    {
        if(convertExpression.NodeType != ExpressionType.Convert)
        {
            throw new ArgumentException("Invalid property expression.", "exp");
        }
        body = convertExpression.Operand;
    }
    return ((MemberExpression)body).Member.Name;
}

用法:

var x = new ObjectType();
// note that in this case we don't need to specify types of x and Property1
var propName1 = GetPropertyName(() => x.Property1);
// assumes Property2 is an int property
var propName2 = GetPropertyName<ObjectType, int>(y => y.Property2);
// requires only object type
var propName3 = GetPropertyName<ObjectType>(y => y.Property3);

更新:修复了返回值类型的属性的GetPropertyName(Expression> exp).

Update: fixed GetPropertyName<TObject>(Expression<Func<TObject, object>> exp) for properties returning value types.

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